From http://www.anyangtrade.net/anyangcity.htm:
The green represents the environmental agriculture and green nature and
The blue symbolizes the clear water of Yangpyeong The ginko tree, with its
history of 1000 years, as its theme, it indicates the confluences of
Namhangang , Bukhangang and Yongmunsan The 'Taegeuk' symbol expresses
Yangpyeong-gun's harmony of agriculture and environment, of nature and
mankind, and of culture and nature All in all, the initial "Y" of
Yangpyeong indicates Yangpyeong stretching out to the bright future lying
ahead.

researched by Phil Nelson, 6 October 2005

While on my recent trip to South Korea, I traveled through Yangpyeong
County in Gyeonggi Province, visiting the Jipyeong-ni battle site. While
there, I noticed that the flag we had for Yangpyeong County is incomplete.
It does, indeed, feature the county logo displayed on a white field.
However, it also has the county name in black Hangul characters beneath the
county logo.Randy Young, 27 November 2014